A fascinating revelation for me from pop-genetics -
You could have a family that's part of an endogamous group for 1000 yrs
Yet 4500 yrs ago:
Dad's patrilineal line may be in Ukraine
Uncle X's in IVC
Grand-Uncle Y's in S.India/SE asia
Today they belong to this single caste

With respect to the broader autosomal ancestry, all these three people will be v v similar if they have been part of same caste for hundreds of years...
Roughly similar Steppe-IVC-AASI split
But patrilineal line as recent as 2500 BCE will place each of them in remote corners

This is borne from my own family's data!
My y-haplo (R1A-Z94) places my patrilineal line likely in the steppe 4500 yrs ago
A couple of distant uncles (related to my father's mother) had L and H respectively
L being Iranic / IVC origin, H possibly AASI

Yet they are all from same caste. And likely have been for 2-3K years in the same varNa at least.
But the patrilineal lines are markedly different

Another insight from pop genetics is that we now most definitely know that "Gotra" is not a super strict marker of common patrilineal descent
We've seen enough cases where people belong to totally different, unrelated y-haplos within same gotra..